If you now loose ssh connection to your FR it does not matter - the upgrade proceeds (as long as the FR does not sleep - if the touchscreen goes black please tap the touchscreen to prevent sleep).

If you do loose the ssh connection, you ought to be able to restart the wi-fi interface, start a ssh connection to FR and reconnect to GNU screen process and see the last couple of lines and see how the upgrade ended.

If you now loose ssh connection to your FR it does not matter - the upgrade proceeds (as long as the FR does not sleep - if the touchscreen goes black please tap the touchscreen to prevent sleep).

If you do loose the ssh connection, you ought to be able to restart the wi-fi interface, start a ssh connection to FR and reconnect to GNU screen process and see the last couple of lines and see how the upgrade ended.